“American Idol 4” changed the rules. Instead of limiting auditions to those aged 16 to 24, producers increased the age limit to 28. The result was the addition of some talented older finalists, such as Bo Bice, Constantine Maroulis, and Nadia Turner. Certain finalists, who were 28 when they auditioned, even turned 29 while the show was continuing, leading to confusion.

After the auditions, which saw the biggest crowds ever (21,000 in DC), and the participation of celebrity guest judges such as Brandy and Gene Simmons, the show moved on to the semifinal round. For the first time, "Idol" featured 12 men and 12 women, who were voted off two at a time each week, thus assuring a top 12 that was evenly split by gender.

The season was infused with several controversies, notably Corey Clark’s interestingly timed claim that he’d had an affair with judge Paula Abdul. But weeks before that, well-liked top 12 contestant Mario Vazquez dropped out of the competition right before the finals began. He cited family-related “personal reasons,” although his mother said she was unaware of any such problems. After leaving, Vazquez hired the same lawyer Clay Aiken used to free himself from the "Idol" contract, and has since signed with Clive Davis’ J Records — the same company that has the option of signing “Idol” finalists.

Many of the other finalists haven’t had time to record and produce a record, particularly since they were touring as a group last summer. Since the show, though, many have made various media appearances, and a few have continued to nurture their Clay-like followings.

Among those with obsessive fans is Ukraine-born Anthony Fedorov, who recovered from a tracheotomy as a young child, went on to place fourth in the competition. While he’s yet to sign with a label, he toured with the other finalists, and he’ll appear on the reality show “Fear Factor” this February with Carmen Rasmusen from the second season.

Former mail carrier Vonzell Solomon placed third. Although she left her post office job, she’s maintained a connection to the organization. Along with Nat King Cole, Nick Lachey, and Alicia Keyes, Vonzell was featured on a postal-service CD collection called “Dear Santa,” produced as a tie-in for a FOX special.

But it was two of the show’s older contestants, both more rock than pop, who have had the greatest success among the losing finalists. Constantine Maroulis, who ended up in sixth place, returned to his band “Pray for the Soul of Betty” after the show. He’s now working on a solo album — and a television sitcom. Besides performing musically, Constantine has also worked as an actor on Broadway and in films. More significantly, Kelsey Grammer’s production company is working on a show for ABC that’s based on Constantine’s life. Constantine will star in the show, which will shoot a pilot episode next fall.

Slideshow: Celebrity Sightings
The other rocker of season four, Bo Bice, made it to the final two. Touring with “Idol” over the summer, he broke his foot while performing. In August, he left the tour for emergency surgery related to intestinal blockage, and complications sent him back to the hospital in mid-December. Despite those setbacks, he’s done very well. Shortly after “Idol” ended, he and his girlfriend were married, and they had a son, Aidan, in September. They eventually left Alabama for Nashville, and the couple offered their Alabama house to a family who lost theirs during Hurricane Katrina. Bo’s solo album, “The Real Thing,” which was released in mid-December, debuted at number four, and last summer, his first single, "Inside Your Heaven," debuted at number one, bumping Carrie Underwood’s version of the same song from the top of the single’s chart.

Still, it was Carrie Underwood, the winner of “American Idol 4,” who sold more copies of the single in its first week. She was only the third artist in the chart’s history to debut at number one — and other two, Clay Aiken and Fantasia, were “Idol’ runners-up and winners respectively.

Like Kelly Clarkson, Carrie took home the prize after never ending up in the bottom three, so she was never threatened with elimination.

Her fans have kept her successful; last fall, her first album, “Some Hearts,” debuted at number two, with more copies sold than either Fantasia or Kelly Clarkson sold in their first weeks. Carrie’s album went platinum a month later, and by mid-December, had sold almost 1.5 million copies. Also in December, she won three Billboard music awards.

Who will be the next performer to capture our hearts or our hatred? Who will sell albums, and who will fade into obscurity? Whose fans will be slighted, and whose fans will be elated? Which auditioners will become instant celebrities, and which ones will make our ears bleed? We’ll learn the answers to these questions when “American Idol 5” debuts Jan. 17.